This invention relates to processes for separating metals. More particularly, it is concerned with a process for separating tungsten from the coinage metals, notably silver, during electrowinning.
In the manufacture of electrical switchgear equipment, relays, motor controllers and the like, composites or alloys of tungsten with the coinage metals, especially silver, are used as electrical contact points. Cost considerations dictate that both tungsten and silver be recovered from any scrap generated by the manufacturing process.
It has been the practice in the art to recover silver or other coinage metal from tungsten-containing alloy scrap by conventional electrowinning techniques. A major drawback, however, is the contamination of the coinage metal collected at the cathode of the electrowinning cell with unwanted tungsten inclusion.